Black dots on applied normal map
Your normals are facing the wrong direction (as evident by the yellow color on your normal map that you have circled). 

First thing you'll want to do is familiarize yourself with what normals should look like. You've circled some areas in your map that demonstrate the problem. Here are two images that go over all the different colors a normal map could be in tangent space.




The image on the left has appropriate colors, the image on the right has colors you want to avoid. If you look at the areas you circled, you'll see they are that muddy yellow and do not transition smoothly with the surrounding area, indicating a problem.

So how were these two images made? By baking the same hemisphere and simply inverting their normals:




In case you're not familiar with this display, the blue lines indcate the direction of the normal on each face, the spheres were baked to the plane below it. You'll notice that the sphere on the right has its normals pointing in the direction opposite of the plane, this will generate the image on the right. 




Here's a simplified version from the side. With the normals of the plane shown.

So what could have caused it? Well it looks like you were playing around and sculpting. You were probably pushing and pulling the faces and ended up with something that looked like this: 



If it were just the mesh (its not in this case, its the normal map) you could fix it by hitting ctrl+n in edit mode, which attempts to repair your normals. Since (Im assuming) this was a sculpt, you can attempt to use ctrl+n on the sculpt, or you'll need to find the problem areas and manually fix the geometry then rebake the normal map.